A backdoor (also known as a trap door or wormhole) in a computer system is a method of bypassing normal authentication, securing remote access to a computer, obtaining access to plaintext while attempting to remain undetected. Backdoors may take the form of an installed program (e.g. Back Orifice) or could be a modification to an existing program or hardware device.

A backdoor in a login system might take the form of a hard coded user and password combination which gives access to the system. It should be stated, however, that the motivation for such holes in the security of a system is not always sinister; some operating systems, for example, come out of the box with privileged accounts intended for use by field service technicians or the vendor’s maintenance programmers.

In the context of coding and hacking a backdoor is a special way to gain access to a system or network. It originally referred to code that allowed the programmer to access a system they had designed without going through the proper procedures. When malware is concerned, a backdoor is a program that allows the attacker to gain unauthorized access to a system. Remote access tools (RATs) are software solutions designed to provide a way for experts to provide remote assistance. However, the same tools can be used by cybercriminals to wreak all types of havoc

How Does a Backdoor Work?

While backdoors in and of themselves don’t do direct damage, they should be treated as severe threats. Backdoors can allow cybercriminals access to a system and they are the backbone of the most devastating attacks. For example, backdoors can allow the installation of ransomware which is one of the prevalent and serious threats. Backdoors can also enable attackers to infiltrate a device on a network. Then they can facilitate the lateral movement of the criminal in the network ultimately compromising the entire network. Such breaches can remain undetected for long periods of time and result in data theft and other damages.

There are different types of backdoors, i.e. IRC, RAT, although all are built to bypass normal security measures and allow a hacker to secretly and remotely gain control of a system and its internet and network connection. Backdoors are typically comprised of two components – a client application (hacker’s end) and a server application (malicious component installed on an infected system). Depending on the malware builder’s goal the level of sophistication of the client application and use can vary. For example, a backdoor could allow:

  • An ability to gain administrative control and reconfigure the infected system, including file deletion, creation, relocation, edits, etc.
  • An ability to execute remote shells or type directly into command prompts
  • An ability to send and receive files
  • An ability to snap screenshots or capture keystrokes
  • An ability to control mouse movements or enter keystrokes
  • An ability to gather system data
  • An ability to survey drives, i.e. hard drive, network drive, external drives
  • An ability to change settings, i.e. date/time, etc.
  • An ability to open or close CD-ROM tray
  • An ability to shutdown the system
  • An ability to visit malicious websites that encourage click fraud or promote rogue programs

Many Malware Types have Backdoor Functions

Some trojans are multilayered and have backdoor capabilities, thus are categorized as backdoor trojans or remote access trojans. Like trojans, backdoors may be cloaked inside the download of freeware or shareware or carried inside via an infectious link or attachment wrapped in a cleverly written or spoofed email spam communication. Computer worms as well as trojan droppers (or downloaders) can install backdoors. Without adequate antimalware protection, any connection over the Internet is vulnerable to attacks or misuse.

As mentioned earlier, most malware is dependent on human aid whether a click on a link or landing on a malicious or compromised webpage housing an aggressive and sophisticated trojan downloader. Avoiding such traps can be difficult for inexperienced and experienced users alike. However, there are many cybersecurity solutions that are capable of preventing and/or dealing with most malware infections. Equally important is implementing safe habits when using the Internet.

All malware programs, including backdoors, often co-exist or work alongside other malicious programs. The primary goal of malicious programs is to cause harm, whether that involves the theft of data, opening a backdoor, or causing interruption to normal use. Backdoors and many other malicious programs are face-less (i.e. without an interface) and are designed to work quietly in the background while the victim is none-the-wiser. Malicious system changes or overload of system resources, such as the launching of a DNS strike, may prematurely expose the infection after negatively impacting system performance. At the first sign of malicious behavior, you should use a trusted anti-malware scanner to investigate. Because a lot of today’s malware is using obfuscation tricks to prevent detection, it is suggested you get professional help to counter severe threats.

Malware makers love to take something meant of good and use it for bad. Backdoors were modeled off of remote assistance tools (RATs), initially created to offer remote aid to novice PC users whose PCs needed troubleshooting or maintenance. Years past, remote administration utilities were largely used by corporations employing remote workers. Today, however, unbeknownst to many PC users, many software programs use a backdoor elements, which may be necessary for their basic function. With malicious backdoor programs, hackers leverage those capabilities for malicious purposes.

Most Trending Backdoors in the Last 2 Weeks

# Threat Name Severity Level Alias(es) Detections
1. Backdoor.Salgorea 60 % (Medium)
2. Trojan-PWS.Win32.LdPinch
3. EUR:Backdoor.Win64.Generic
4. Backdoor:Win32/Qakbot!lnk 60 % (Medium)
5. CallMe
6. Backdoor: Win32/Turkojan.AI 60 % (Medium) Heuristic.BehavesLike.Win32.ModifiedUPX.C
7. Saitama Backdoor
8. Facefish Backdoor
9. Backdoor.SDBot 60 % (Medium) W32/Cryp_PESpin.U!tr
10. Backdoor:IRC/Rxbot 60 % (Medium) Gen:Variant.Kazy.5565
a variant of Win32/Olmarik.AJE
11. Backdoor.Netbus.1_70 60 % (Medium) Trj/Netbus.J
12. Backdoor.Breut 20 % (Normal) 16
13. DarkComet 60 % (Medium)
15. Sagerunex
16. RDAT Backdoor Trojan
17. Wirenet Backdoor
18. NginRAT
19. Ebury
20. Horse Shell Malware
21. Backdoor.Bifrose 60 % (Medium) Generic25.CJCV
22. Backdoor.Oldrea 20 % (Normal) 1
23. Backdoor:Win32/Zegost.B 60 % (Medium) 25
24. Backdoor.Athena 60 % (Medium) 10
25. Backdoor.Orcus 60 % (Medium) 3,815
26. Ketrican
27. Sardonic Backdoor
28. SysJoker Backdoor
29. Electron Bot
30. OSX/NukeSped

Last updated: 2023-08-17

Backdoors List

Threat Name Severity Level Detections
'linux_avp' Malware
'Stromag' Email Scam
'' Pop-Up Notifications
"Nice picture" Backdoor.Agent
ABK Downloader
ABX Trojan
Acid shivers modified 80 % (High) 27
AckCmd 80 % (High) 3
Application.QueryMon 80 % (High) 78
ASPXSpy Malware
BackDoor-AWQ.gen.r 80 % (High) 77
BackDoor-DOQ.gen.y 50 % (Medium) 6
1 2 3 4 5 6 44